1. Field of the Invention
The present invention relates to a signal processing apparatus which includes operating means for manually continuously changing parameters in processing signals and operating means which has another function, and more particularly to a signal processing apparatus which can enhance operability and reduce operation errors.
2. Description of Related Art
As one of business-use apparatuses which are used for editing images in television broadcasting or the like, there has been known an image signal processing apparatus which is referred to as a switcher. The switcher is an apparatus which selects and outputs video signals from inputted video signals (video signals from a video camera, a VTR or the like) of a plurality of channels or applies an effect to transit outputted video signals from one video signals to another video signals (a transition effect).
The switcher is, in general, constituted of a switcher body and a control panel. On the control panel, as operating means, a plurality of push buttons is mounted together with a fader.
The fader is operating means for manually and continuously (sequentially) changing a parameter indicative of an output rate of two video signals by moving a slide-type lever from one end portion to another end portion in applying the above-mentioned transition effect.
To the push buttons, a function of controlling a switcher body (selection of an input signal, display of characters or the like), a function of controlling an external equipment (VTR or the like) or the like are allocated.
In editing the images using the switcher, in an interlocking manner with the operation of the fader, at timing that two video signals assume a specific output rate, in many cases, it is necessary to execute another function. For example, a case in which a VTR is controlled at timing that two video signals assume a specific output rate, and another video signal which is displayed while being sandwiched between two video signals is reproduced by the VTR may correspond to such a case. Further, a case in which characters are displayed in response to one of two video signals at timing that two video signals assume a specific output rate also corresponds to such a case.
Conventionally, to execute another function in an interlocking manner with the operation of the fader in this manner, an operator operates a push button with one hand at a suitable timing while operating the fader with the other hand or another operator takes charge of operating the push button and two operators perform the operation at proper timing in a cooperating manner.
Here, as the image signal processing apparatus having the fader, there has been also proposed an image signal processing apparatus even when a lever of a fader is moved to an end portion, the transition to a video signal after switching is not completed and such movement provides a halfway state (see JA-A-2004-173074 (paragraphs 0054 to 0058, FIG. 5), for example). However, such an image signal processing apparatus also has a drawback that it is necessary to operate both of the fader and the push button to execute another function in an interlocking manner with the operation of the fader.